In recent years, a display device with a large screen has been used for a wide variety of applications, such as a signage and an information display. With this trend, there have been increasingly developed a single display providing a large screen display and a large-screen display system including multiple displays in which a plurality of displays are arranged in a matrix manner.
A liquid crystal panel display includes: a liquid crystal panel including two glass substrates between which a liquid crystal material is sealed; and a backlight provided on a back side of the liquid crystal panel. Such a display provides image display by driving the liquid crystal panel in response to an incoming image signal from an external apparatus such as a PC (personal computer) or a reproducing apparatus.
A liquid crystal display device includes a gate driver and a source driver, each of which serves as a circuit for driving the liquid crystal panel. The gate driver and the source driver, which are connected to a gate and source of a transistor for driving each pixel of the liquid crystal panel, (i) control turn-on/turn-off of the transistor in accordance with an incoming image signal and (ii) apply, to the transistor in the on position, a voltage (input level of input to the liquid crystal panel) corresponding to the image signal, thereby changing optical transmittance determined by electro-optical characteristics of the liquid crystal material. With this arrangement, the liquid crystal display device can produce tone by controlling, for each pixel, the amount of light transmitting the liquid crystal panel upon illumination from the backlight.
As for the liquid crystal panel, the electro-optical characteristics of the liquid crystal material are determined by a so-called cell gap, which is a distance between the glass substrates between which the liquid crystal material is sealed. Due to a manufacturing variation or for other reason, the liquid crystal panel can include pixels having varying cell gaps whose values are deviated from their design values. This can cause deviation of the optical transmittance of the liquid crystal panel from its design value, with the result that an unsatisfactory gamma characteristic (display non-uniformity) of the liquid crystal panel is obtained.
Meanwhile, the above large screen display system can have the problem of differences in gamma characteristic and output color between the displays provided therein, due to non-uniform display characteristics of the displays.
In view of this, there has been proposed a system in which an image of a display section of a display device is captured, and information on luminance values and output color, which information is obtained from data of the captured image, is then stored together with positional information, so that a calibration process for performing display non-uniformity correction is carried out to provide uniform display.
For example, Patent Literature 1 proposes a multi-projection system, wherein a screen onto which separate color images are projected by projectors is divided into a plurality of small regions, and brightness and color characteristics of each of the small regions are measured and then stored, as a profile, together with its positional information. In the system, the screen onto which separate color images are projected by the projectors is divided into an arbitrary number of small regions during the projection, a profile is selected in accordance with the positional information of the small region, and the separate color images are then subjected to color conversion using the selected profile so that brightness and color corrections of the images are performed. Consequently, a high degree of color reproduction is achieved across the entire screen.